Ventilating-fan.



No. 632,740. Patented Sept. l2, I899. H. L; PARKER.

VENTILATING FAN.

(Application filed Sept. 9, 1898) (Model.)

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U ITED STATES PATENT OFFICE.

HERBERT L. PARKER, OF ST. LOUIS, MISSOURI, ASSIGNOR TO THE EMERSON ELECTRIC MANUFACTURING COMPANY, OF SAME PLACE.

VENTILATING-FAN.

SPECIFICATION forming part of Letters Patent No. 632,740, dated September 12, 1899.

Application filed September 9, 1898. Serial No. 690,555. (ModeL) To all whom it may concern.-

Be it known that I, HERBERT L. PARKER, a citizen of the United States, residing at the city of St. Louis, State of Missouri, have invented a certain new and useful Improvement in Ventilating-Fans, of which the following is a full, clear, and exact description,

such as will enable others skilled in the art to which it appertaius to make and use the to same, reference being had to the accompanying drawings, forming partof this specification, in which- Figure 1 is a plan View of my improved ventilating fan. Fig. 2 is an edge View of the same; and Fig. 3 is a side elevational view of the motor on which my improved fan 'is mounted, illustrating in conventional form the direction of the air-blast by the fan.

This invention relates to a new and useful improvement in ventilating-fans of that class which are commonly employed in connection with electric motors, whereby a blast of air will be delivered by the fan to keep up a circulation of the air in the room.

The objects of my present invention are to so construct the blades or flights of the fan that less power is required to operate the same and also to so construct the fan-blades that they will rotate freely and without noise.

The type of blades most usually employed in ventilating-fans of this character are radially disposed from the shaft and set at a slight angle or pitch, each blade being bent longitudinally, so as to shed the air with as little resistance as possible. The construction of such a blade confines the air delivered practically at the outer end of the blade,so that in rotation ahollow cylinder of air is thrown forward. In addition to this the rapidity with which these fan-blades are driven causes the blades to vibrate, resulting in a humming noise having a slight metallic twang, almost like that of a planingunill in operation. This noise, as stated, is caused by the 5 rapid rotation of the fan-blades, wherein the air is cut and forced forwardly, there being not suflicient time for the atmosphere at the rear of the blades to rush in to fill the space before the next blade in succession strikes the air. This action is somewhat l ke that of a paddle-wheel of a steamboat, of course modified by the diflerent conditions, and when the blades slap theair they are made to vibrate and emit a metallic whirling sound. In the construction of the fan-blades shown in the accompanying drawings I have so formed the blades that the cuttingedges are at right angles to the shaft, so that all the cutting edges of the different blades travel in the same path, which is only as wide as the thickness of the blade. By doing this the air is not rarefied or pushed back and forth, as is the case with the old style of blades, but is gradually drawn in, the curvature of the blades forcing it gradually forward until finally impelled with force as it is delivered from the blade. To form a solid column of air, I also provide an auxiliary fin at the back of each blade, so that almost as much air is delivered from a point near the axis of rotation as is impelled from the periphery of the blades.

In the drawings, A indicates a spider having as many arms or tlukes a as desired. These arms, as is usual, are arranged at a slight incline or pitch,and to them blades B are secured by suitable rivets Z) or otherwise. Blades B, as shown in Fig.1, are preferably stampedof suitable metal, and before being attached to arms a are slightly curved, as shown. The cutting edge C of the blade has an irregularly-curved contour, the portion midway the outer and inner ends of the blade being most prominent. This curvature is preferably such that from a point approximately the length of the blade to its outermost extremity the cutting edge recedes in a gradual curve, so that in operation this receding portion makes a shearing out. Then the blades are secured to the arms a and given their pitch relative to the shaft, the curve at the cutting edge C would ordinarily be out of a straight line relative to the shaft, so that said blade would be unbalanced. By transversely curving the blade, however, the curved cutting edge C is brought into a plane at right angles to the axis of rotation of the shaft, as shown in Fig. 2, so that when the fan is rotating said cutting edge meets with little or no resistance, (only its thickness,) and by reason of the receding zoo curved portion the blade easily shears or cuts the air, forcing or wedgin g the air forwardly.

D indicates the working face of the fanblade, which commences slightly back of the cutting edge and continues rearwardly to the rear edge of the blade. This working face is formed with a fin E, obliquely disposed to the shaft, so that the tendency of said working face when the fan is rotating will be to shed the air forwardly and outwardly in the shape of a frustum ofa cone.

F indicates a fin at the rear edge of the fanblade, which is designed to travel in a path of less diameter than the fin E. Fin F is bent obliquely practicallyparallel with fin E, so as to form a working face G, whose function is to shed the air adjacent 'to the axis of rotation of the fan and in this way form a solid column of air instead of a hollow cylinder of air, as has heretofore been done by the ordinary straight and radially-arranged fanblades. Of course it will be understood that in the event the fan-blades are longer additional fins can be added to increase the capacity of the blade.

I do not wish to be understood as confining myself to the exact angle at which these fins are bent nor to the direction in which they tend to impel the air, as it is obvious that they can be bent at varying angles to deliver the air in different directions.

By arranging the arms or supports a with a slight pitch the fan-blades are given a corresponding pitch. The longitudinal bend extending nearly throughout the length of each blade strengthens said blades considerably to resist vibration. This bend likewise accommodates the irregular-curved cutting edge, so that said cutting edge will form a straight line at right angles to the axis of rotation. By alining the cutting edge of each blade said blades are not subjected to back pressure or torsional strain. The fins at'the rear portion of the blade are by being bent stiffened to resist torsional strains and in operation throw large volumes of air with little or no noise. In fact, by the construction of the blades shown in the drawings the fan will run at high speeds and do more work than the old style of fans with straight blades of the same diameter and with practically no noise. Of course the volume of air thrown forward makes a rushing sound but the sound is not objectionable, as the metallic ring is entirely absent, and, moreover, this rushing sound of the air cannot be heard at a great distance from the fan.

I am aware that minor changes in the construction, arrangement, and combination of the several parts of my fan can be made and substituted for those herein shown and described Without in the least departing from.

with a curved forward edge, that portion near the outer edge of the blade gradually receding in a curved line to efiect a shearing cut, and said blade being bent longitudinally to throw said curved forward cutting edge in a plane at an angle to the axis of rotation; substantially as described.

2. The combination with a suitable support, of fan-blades arranged thereon, each of said blades being formed with curvedcutting edges, that portion midway the outer and inner ends of the blades being most prominent, from which prominent portion the outer cutting edges gradually recede to effect ashearing cut, and said blades being bent longitudinally to aline their cutting edges in the same plane at an angle to the axis of rotation; substantially as described.

3. The combination with a supporting-spider, of fan-blades B, mounted thereon, said blades being formed with cutting edges C, having an irregularly-curved contour,the portion midway the outer and inner ends of the blades being most prominent, said blades being bent longitudinally to bring their cutting edges into the same plane at right angles to the axis of rotation thereof, the working face D, which'commences slightly back of said cutting edges and continues rearwardly to the rear edge of the blade, terminatingin a fin E, obliquely disposed to the axis of rotation, whereby the tendency of said working face is to impel the air forwardly and outwardly in the shape of a frustum of a cone; substantially as described.

4. The combination with a supporting-spider, of fan-blades B, mounted thereon, said blades being formed with cutting edges 0, having an irregularly-curved contour, the portion midway the outer and inner ends of the blades being most prominent, said blades being bent longitudinally to bring their cutting edges into the same plane at right angles to the axis of rotation thereof, the working face D, which commences slightly back of said cutting edges and continues rearwardly to the rear edge of the blade, terminating in a fin E, obliquely disposed to the axis of rotation, whereby the tendency of said working face is to impel the air forwardly and outwardly in the shape of a frustum of a cone, and afin F, also arranged at the rear edge of the blade, nearer the axis of rotation than fin E, said fin F being bent obliquely to said axis of rotation to form the working face G,whose function is to impel the air adjacent to the axis of rotation of the fan; substantially as described.

In testimony whereof I hereunto affix my signature, in the presence of two witnesses, this 6th day of September, 1898.

' HERBERT L. PARKER.

Witnesses:

R. CORNWALL, HUGH K. WAGNER. 

